The present invention relates to a ligation instrument, which is used during ligation of stomach or esophageal varices and internal hemorrhoids, that enables safe and ensure treatment through simple manipulation.
Endoscopic variceal ligation (hereafter referred to as EVL) is performed to treat varices of the stomach and the esophagus caused by hepatocirrhosis or other reasons. EVL is a manipulation performed as follows. Referring to FIG. 36, a varix (39) is drawn into a cylinder (38) connected to a front portion of an endoscope (2) so that the varix becomes fungus-like. A ligating ring (13), which is fitted beforehand about the front portion of the cylinder (38), is removed by manipulating a wire inserted through a forceps passage (43) (refer to FIG. 35) and hooked to the basal section of the fungus-like varix (39). The elasticity of the rubber ligating ring (13) mechanically ligates the varix (39).
U.S. Pat. No. 4,735,194 describes a conventional ligation instrument, which is shown in FIG. 35, used when performing EVL. The ligation instrument has a cylinder (38) fixed to a coupling portion (40) defined at the front end of an endoscope (2). A slide tube (4), to which a ligating ring (13) is fitted, is fitted in the cylinder (38) so that the slide tube (4) can slide within the cylinder (38). The slide tube (4) is fixed to a trip wire (41), which extends through a forceps passage (43) of the endoscope (2). In this structure, when the trip wire (41) is pulled, the slide tube (4) is retracted, and the front end of the cylinder. (38) is separated from the ligating ring (13).
FIG. 34 shows a different ligation instrument, which is used to perform EVL and is driven by air. A slide tube (4), the rear end of which is surrounded by a seal ring (7), is provided between an inner tube (5), to which a ligating ring (13) is fitted, and an outer tube (3),. These parts define a hermetic space, the rear end of which is provided with a small hole. The small hole is connected to a fluid tube (9) (refer to Japanese Unexamined Patent Publication No. 7-059786, U.S. Pat. No. 5,507,797). In this structure, a syringe (44) forces air through a connector (45) and a fluid tube (9) to extend the slide tube (4) and separate the ligating ring (13).
In each of the ligation instruments, only one ligating ring (13) is connected to the inner tube. Thus, to perform the ligation treatment on a plurality of varices (39), the endoscope must be taken out of the body cavity every time to attach a ligating ring (13) and then returned into the body cavity. Accordingly, to perform ligations on a plurality of varices (39), the endoscope (2) must be moved in and out of the body cavity a number of times in correspondence with the number of varices (39). This lengthens the treatment time and subjects the patient to a large amount of pain.
To solve this problem, many ligation instruments that perform ligations successively with the endoscope (2) kept in the body cavity have been proposed (e.g., Japanese Unexamined Patent Publication No. 8-10217, Japanese Unexamined Patent Publication No. 8-502198, Japanese Unexamined Patent Publication No. 9-500811, Japanese Patent No. 2561223, Japanese Patent No. 2657427, U.S. Pat. No. 5,398,844, U.S. Pat. No. 5,462,559). However, these instruments use wires similar to that of the ligation instrument: shown in FIG. 35 and still do not provide solutions to various problems. These problems are:
(i) The single forceps passage (43) in the endoscope (2) cannot be used;
(ii) When the endoscope (2) is strongly reversed, sufficient force may not be transmitted to the front end of the trip wire (41) even if the trip wire (41) is pulled strongly. This may hinder the separation of the ligating ring (13);
(iii) It is difficult to perceive the separation of a ligating ring (13). Thus, a ligating ring (13) may not be separated or a plurality of the ligating rings s(13) may accidentally be separated at the same time; and
(iv) The attached ligating rings (13) block the operator""s view.
The conventional ligation instrument of FIG. 34 may solve problems (i) and (ii) but cannot not solve problems (iii) and (iv). Further, it cannot perform ligation successively with the endoscope (2) left in the body cavity.
The present invention provides a solution to the above problems. It is an object of the present invention to provide a successive ligation instrument that performs ligation successively in a safe and ensure manner with the endoscope remaining in the body cavity.
In a successive ligation instrument for ligating a lesion, a fluid is charged into a distal device attached to an endoscope to apply pressure to push forward and separate a ligating ring attached to the distal device. The present invention is characterized by a pressure applying means for charging the fluid into the distal device, and a controller connected to a fluid circuit to control the movement of the ligating ring to sense a pressure drop that occurs in the distal device when one or a plural number of the ligating rings are separated. The movement of the ligating rings is stopped in, accordance with the pressure drop so that at least two or more of the ligating rings are separated.